Etching and decorating metal surfaces



March 11, 1930. J. c. MCFARLAND 1,750,418

` ETCHINCTAND DECORATING METAL SURFACES n Filed Deo.' 5, 1928 wade l Patented Mai'. 1l, 1930 UNITE STATES PATENT OFFICE JAMES MCFARDAND, OF FORT THOMAS, KENTUCKY, ASSIGNOR TO THE WADSWORTH WATCH CASE CO., F DAYTON, KENTUCKY, A CORPORATION OF KENTUCKY Application filed December 5, 1928. Serial No. 324,024.

rlt`his invention relates particularly to a method of decorating and/ or etching metal surfaces. The invention relates m-ore especially to a method of decorating base metal surfaces as by plating and/or etching.

The primary ob]ect is to and effective method which is Well adapted for use in decorating the surfaces of base metals, such as steel, 12% nickel alloy, etc. m A. nickel alloy of the character just referred to and Which is in co'mmon use is composed of Ni, 12%; Cu, 70%; Zn, 18%.

lThe invention/Will be described first with reference to the treatment of a steel plate, or 15 block, by Way of example. Suc-h method is illustrated in the accompanying drawing, in Which Fig. l represents a base plate, which may be of steel; Fig. 2 is intended to illustrate the application of a copper plating to the base plate; Fig. 3 illustrates a further step in which a suitable resist design is applied to the copper plating; Fig. 4t represents a further step in Which `the exposed areas of copper are removed, as by means of a suitable solvent for copper; Fig. 5 illustrates a further step in which the resist design has been rc'- inoved, leaving areas ofthe original metal expo-sed and other areas covered with the copper plating; Fig. 6 illustrates a further step in which a chromium plating is applied to the exposed areas of the steel plate, so that the plate now bearsV a design in copper plating and a compleinental design in chromium plating; Fig. 7 illustrates a fui'ther step in which the remaining copper plating is removed; and Fig. 8 represents a further step in which gold'plating is applied to the newly exposed areas of the steel surface, so that the 40 steel plate now has a surface composed of a chromium plating design and a complemental gold plating design. y y

l If desired, a further step may be used.

Y That is, the remaining chromium plating may' be'removed and the newly exposed surfaces of provide a simple the steel plate may be etched, Whilst the gold plating serves as a resist. This step may be followed by a further step in which the etched areas of the steel plate are given a plating contrasting in color with the gold plating.

In appl-ying a chromium plating as illustrated in Fig. 6, one uses` a suitable current density (amperage per unit of area), Which Will result in the steel areas taking the chromium plating, vvhile the copper areas Will not receive the chromium plating. Methods enabling this to be accomplished are known in the art.

Referring to Fig. 81, the expo-sed steel surfaces Will receive the gold plating, While the chromium plating will not receive the gold plating.

lf desired to remove the chromium plating shown in Fig. 8, a suitable solvent for the purpose isdilute hydrochloric acid, or dilute sulphuric acid. Chromium plating is hard,

resistant andvfree from tarnishing. lt possesses a color somewhat similar to aluminum. it therefore afords a ,color which contrasts 4with the gold color andy may be allowed to remain as a desired.

Any precious metal, or precious metal alloy, may be usedl in lieu of gold. Where complemental designs of different metals aredesired in a complete decorative design, one separt of the decorative design, if

lects metals of contrasting colors.

Ferrie chloride may be used for etching the base plate, Any other suitable plating may be used in lieu of copper plating, as, for exl ample, brass plating.

Brasses, bronzes, German Silvers, etc. may. by suitable variations 1n the process, be used as base plates. One may, in the first instance,

provide a base platewith complemental de-v signs in different metals, and "may then proceed to apply a chromium plating to one of the metals, by usingsuitable conditions for effecting the deposit of the chromium platin g upon one of the inetals and not on the other.

rl`he chromium plating may then serve as a resist while a precious metal plating is being applied to the areas not covered by the chromium plating. Finally, the chromium plating may be removed, or not, as desired; and if removed, the newly exposed metal may he etched, and the etching operation may be followed by a further plating operation, if desired.

rlhe resist design may be applied in any suitable manner, as bya transfer method, or by a photographic method. in the example given above, the resist design preferably is produced by applying to the copper plating a light-sensitive varnish; photographically producing an image in the varnish and nally subjecting the film to a feveloping open ation which dissolves the unreacted portions of the varnish, thus leaving a. suitable resist design upon the copper plate.

Where the base plate is of steel, nitric acid may be used for etching the plate. Any suitable etching agent may be used, depending upon the metal of 1which the base plate is composed.

The foregoing detailed description has been given for clea'rness et understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should he construed as broadly as permissible, in view of the prior art.

lilhat l regard as new, and desire to secure by Letters Patent, is:

l. rllhe method off treating a metal surface, which comprises: producing complemental designs in dil'lerent metals; and subjecting the surface to an electroplating operation with chromium at such current density as to cause the chromium plating to Vbe applied to one design and not to the other.

rlhe method of treating a base metal surface, which comprises: applying a metal plating to the surface; applying a resist design to said plating; .removing said plating at the exposed areas; andA electroplating With chromium the areas of one metal by employing a current density which will cause the deposition of the chromium upon such metal without plating the other metal.

3. 'lhe method of treating a base metal surface, which comprises: plating the surface; applying a suitable resist design to said plating; dissolving said plating at the unprotected areas; removing said resist design; electroplating with chromium the areas presented by one of the metals, using such current density that the other areas will not be plated; removing by 'means of a suitable solvent the remainder of the inst-mentioned plating; and plating with precious metal the last exposed areas.

4. The method of treating a base metal surface, which comprises: plating the surface; applying a suitable resist design to said plating; dissolving said plating at the unprotected areas; removing said resist design; electroplating With chromium the areas presented by one of the metals, using such current density that the other areas will not be plated; removing by means of a suitable soi- Vent the remainder of the first-mentioned plating; plating with precious metal the last exposed areas; removing the chromium plating; and etching the surface exposed by the removal of the chromium plating.

JAMES C. MCFARLAND. 

